Vinylpyrrolidone polymer and its stabilization and preservation processes

Abstract

The present invention provides: a vinylpyrrolidone polymer which exhibits good heat resistance and storage stability; a composition containing the vinylpyrrolidone polymer; a stabilization process for the vinylpyrrolidone polymer, and a preservation process for a vinylpyrrolidone polymer by which: even when the vinylpyrrolidone polymer is preserved for a long time or at high temperature, the physical properties such as molecular weight (K value) of the vinylpyrrolidone polymer can be prevented from changing, therefore the vinylpyrrolidone polymer can stably be preserved. To enhance the heat resistance and the storage stability, a vinylpyrrolidone polymer is mixed with a certain amount of antioxidant, and the oxygen concentration is suppressed to not higher than 50,000 ppm in a gas phase that contacts with the vinylpyrrolidone polymer when preserving.

What is claimed is:  
     
       1. A preservation process for a vinylpyrrolidone polymer, which comprises the step of suppressing the oxygen concentration to not higher than 50,000 ppm in a gas phase that contacts with the vinylpyrrolidone polymer. 
     
     
       2. A preservation process for a vinylpyrrolidone polymer according to  claim 1 , which further comprises the steps of putting the vinylpyrrolidone polymer into an airtight container and evacuating the container. 
     
     
       3. A preservation process for a vinylpyrrolidone polymer according to  claim 1 , which further comprises the steps of putting the vinylpyrrolidone polymer into an airtight container and displacing air in the container with an inert gas and/or carbonic acid gas. 
     
     
       4. A preservation process for a vinylpyrrolidone polymer according to  claim 2 , which further comprises the steps of putting the vinylpyrrolidone polymer into an airtight container and displacing air in the container with an inert gas and/or carbonic acid gas. 
     
     
       5. A preservation process for a vinylpyrrolidone polymer according to  claim 1 , which further comprises the steps of putting the vinylpyrrolidone polymer into an airtight container and enclosing at least one deoxidizing agent together with the vinylpyrrolidone polymer in the container. 
     
     
       6. A preservation process for a vinylpyrrolidone polymer according to  claim 4 , which further comprises the steps of putting the vinylpyrrolidone polymer into an airtight container and enclosing at least one deoxidizing agent together with the vinylpyrrolidone polymer in the container.